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Abstract  

We have developed a thermogravimetric system (TG system) for condensable gas adsorption by modifying a standard thermogravimetric analyzer Cahn TG 2121 and performed isotherm measurements of water vapor adsorption on Fuji Davison type RD silica gel and ethanol vapor adsorption on Maxsorp II activated carbon. For the water vapor-silica gel data, our results compare favorably with the data reported by the manufacturer and those obtained from a volumetric method. This confirms the reliability of our TG system for adsorbents which do not swell significantly. In addition, our isotherm data also provide useful design information for the development of adsorption chillers.

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Abstract  

The surface reactions of uranium metal with carbon monoxide at 25 and 200 °C have been studied by X-ray photoelectron spectroscopy (XPS); respectively. Adsorption of carbon monoxide on the surface layer of uranium metal leads to partial reduction of surface oxide and results in U4f photoelectron peak shifting to the lower binding energy. The content of oxygen in the surface oxide is decreased and O1s/O4f ratio decreases with increasing the exposure of carbon monoxide. The investigation indicates the surface layer of uranium metal has resistance to further oxidation in the atmosphere of carbon monoxide.

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Abstract  

The surface structure of triuranium octaoxide (U3O8) and the effect of CO on surface behaviour have been studied by X-ray photoelectron spectroscopy (XPS). An intensity analysis of the composite U4f photoelectron spectrum of U3O8 shows that this compound should be written as U2 VIUIVOg. After exposure to 7.2·106 L CO (1 L=1.33·10–4 Pa·s), the oxygen content in the surface is decreased and the O1s/U4f ratio decreases about 10%. The investigation indicated that the surface layer of triuranium octaoxide was partially reduced in the atmosphere of carbon monoxide.

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Maize seeds from inbred line Mo17, susceptible to Sugarcane mosaic virus (SCMV), were investigated for SCMV seed transmission. The seed quality significantly influenced the seed transmission rate. There were more infected seedlings derived from larger seeds than smaller seeds in both golden (G) and buff (B) seed groups, the proportion of infected seedlings in G1 was similar to G2 and B1, and significantly higher than the others (P < 0.05 or P < 0.01). While the proportion of SCMV seed transmission was higher in golden (3.9%) than buff seeds groups (2.3%), and there were significantly difference (P < 0.05) between the both colors seeds. However the percentage of infected seedlings was closely related to the location of seeds on ears, most infected seedlings were derived from seeds of the middle (Part III) and mid-base regions (Part IV), and the both parts (Parts III and IV) were significantly higher than that of Part I (P < 0.05). Fisher’s exact test indicated that the seed quality was associated significantly with the efficiency of SCMV seed transmission.

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Abstract  

The 'in-diffusion method was used to study the diffusion behavior of Eu(III) in compacted bentonite. The results (K d, apparent and effective diffusion coefficients) derived from the capillary method are in good agreement with the literature data for similar bentonite dry densities and similar radionuclide concentrations, and fits the Fick's second law very well. The method was used to study the effect of solution concentration (10-7-10-3 mol/l) on the diffusion and sorption behavior in compacted bentonite. The experiments were carried out in synthetic groundwater, at room temperature. The results suggested that the diffusion of Eu(III) in the bentonite was independent on the density of bentonite, but dependent on the solution concentration. In agreement to the literature, the K d values from the capillary experiments are in most cases lower than those from batch experiments, they are about one-half to one-third the value to those from batch experiments. The difference between the K dvalues from capillary and batch experiments are a strong function of the bulk density of the bentonite. The results suggest that the content of interlaminary space plays a very important role to the transport of Eu(III) in compacted bentonite.

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Abstract  

A new method of thermal desorption chromatography, in which hydrogen is used as carrier instead of helium, and a water bath instead of an air bath, is presented for determining the specific surface area of uranium compounds. The method proposed has a higher accuracy and a better applicability.

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Study of the immobilization of226Ra

I. Cement solidification of226Ra waste

Journal of Radioanalytical and Nuclear Chemistry
Authors: R. Wang, X. Yang, and Q. Wu

Abstract  

A study of the immobilization for226Ra waste has been carried out. Cement-based concrete was used as a matrix for the solidification of radium waste. The experimental results show that the cement mixture with water/cement between 0.46–0.54 has higher strengh (above 20 MPa), and the compressive strength was not reduced by addition of 1% barite or the radium waste (RaSO4) into the concrete solid.

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Study of the immobilization of226Ra

II. Predictive model of radionuclide leaching behavior in a cement-based solid

Journal of Radioanalytical and Nuclear Chemistry
Authors: X. Yang, W. Zhou, and R. Wang

Abstract  

A three-dimensional leaching model was developed to describe the leaching of radionuclide from a cement-based concrete solid. The film mass transfer and interparticle diffusion were considered simultaneously. On the basis of the derived model the long-term behavior of radium-226 leaching from the waste solid has been quantitatively investigated.

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Abstract  

The interactions of lanthanide ions (Ln3+) with bovine serum albumin (BSA) under mimetic physiological conditions (310.15 K, pH 6.7, 0.1MNaCl) were studied by microcalorimetry. For the first time, based on Two Sets of Independent Sites Model, molar enthalpies (Δr H m1, Δr H m2) and coordination number (n 1, n 2) of the two sets of binding sites with different affinity were obtained directly from the microcalorimetric results. It was shown that the interactions are endothermic and entropy-driving processes. By combining with fluorescence spectroscopy, other thermodynamic parameters (Δr G m1, Δr S m1) were determined for high-affinity specific sites.

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Abstract  

The free-radical bulk polymerization of 2,2-dinitro-1-butyl-acrylate (DNBA) in the presence of 2,2′-azobisisobutyronitrile (AIBN) as the initiator was investigated by DSC in the non-isothermal mode. Kissinger and Ozawa methods were applied to determine the activation energy (E a) and the reaction order of free-radical polymerization. The results showed that the temperature of exothermic polymerization peaks increased with increasing the heating rate. The reaction order of non-isothermal polymerization of DNBA in the presence of AIBN is approximately 1. The average activation energy (92.91±1.88 kJ mol −1) obtained was smaller slightly than the value of E a=96.82 kJ mol−1 found with the Barrett method.

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